Although some people correct children explicitly (we do), the usual route is that they're corrected indirectly when the adult repeats the phrase in some way back to them. Think something like a child saying, "Eat apple!", and the adult saying back to them, "Oh, do you want to eat the apple?" It's more subtle than directly correcting, but it's correcting nonetheless.

And that sort of thing is absolutely helpful when learning a language. When I'm not quite getting my point across, then finally I manage to grudgingly do so and the person says the equivalent of, "Oh! So you mean that you want to eat the apple!", I've got the correct way of saying it right there for the taking.

After I posted this comment, I went back and read Steve's earlier comment where he wrote "[kids] hear it and they imitate it", and began to wonder if this was a to-MAY-to / to-MAH-to thing where I'm calling it "being corrected" and he's calling it "imitating".

In any case, Steve continues:

I simply do not buy it. You cannot possibly correct enough errors to make a difference. Children and most good learners correct most of their mistakes on their own. The brain gradually corrects itself as the patterns of the language become clearer.

OK, I'll draw a line in the sand in response to that. My position, after the jump.

While I generally agree with Steve on most things language learning, the utility of being corrected is one place where we definitely disagree. When Steve touched upon this issue earlier, he wrote:

The idea of perfect strangers correcting my use of language . . . strikes me as just rude, and certainly not helpful.

In contrast, perfect strangers correcting my use of language is always extremely welcome but sadly doesn't happen enough. I definitely find it helpful and I think the difference comes down to how the learner takes the corrections. I've got a post on just this issue in the oven, but for now I'll just flag this disagreement as I think it may add some color to our views on correcting children's language use.

Turning to Steve's comment, I would say that the brain will gradually correct itself as the patterns of the language become clearer, but why wait? My first-hand experience with my daughter has shown me that waiting doesn't pay off. A recent example of a mistake of my daughter's that I corrected was "buyed". I don't recall the exact phrase, but if she had said, "I buyed it", I'd've probably said, "No, you gotta say, 'I bought it'" and, used to the routine, she'd just repeat, "I bought it", without missing a beat and the conversation would continue. Typically she'll use the word again soon in the conversation, e.g.: "What'd you buy?" "I bought..." So, while the brain will gradually figure out the rule from passive exposure (listening), she just had two repetitions of active exposure (speaking), which I always find to be even better for getting something in your head; once you can use it correctly yourself, you've burned some pretty good paths in your brain to that piece of knowledge.

Sometimes I'll even explain the rule to her. When she was having trouble with "geese" being the plural of "goose", I told her that that word is "weird" because, instead of adding an "s", it changes to "geese". After telling her that, the next few times she encountered the word she paused to tell me the rule and then said it correctly. Now she just knows it. In fact, she now actively asks why something doesn't fit into the rules as she understands them (just today I was asked why "fish" doesn't become "fishes" in One Fish, Two Fish, Red Fish, Blue Fish).

I think in any of the examples above it would have taken her a lot more time to get enough exposure to "bought", "geese", etc., to have figured the rules out on her own, although I don't doubt at all that she eventually would have.

The end result of all this is that instead of spending more time trying to learn these passively, she'll get them more quickly and move on to something else. And, although far short of a scientific control, there's actually some basis for comparison with my daughter. My wife, who speaks Japanese with my daughter, corrects her about as much as I do in English. However, we've had Chinese nannies and babysitters teaching her Chinese for most of the time she's been speaking, and they are generally less stringent about corrections. While living in the States when her exposure to Japanese and Chinese was roughly equal, her Chinese mistakes would linger much longer than her Japanese mistakes. So, while she was moving ahead in terms of grammar and vocab in Japanese, she was progressing more slowly in Chinese. I think the amount and efficacy of the corrections she was receiving was one factor in this.

Based on the above, I obviously don't think that we can't "possibly correct enough errors to make a difference". Beyond the results we've seen, this is really no different than any other spaced-repetition system. If she makes the same mistakes over time, she gets a repetition of that piece of information. If the typical spaced-repetition system requires five or six repetitions to generally learn something, why would kids be any different?

In sum, I feel like I'd be doing her a huge disservice by not correcting her and just letting her "brain gradually correct itself as the patterns of the language become clearer". That'd happen, for sure, but I can't see how it'd be the most efficient way to go about it.

There's truly a lot to learn, and much of it will be picked up over time, but i agree that there are certain words that may be more difficult for a certain person, and they are usually relatively few.

Your example of some of the irregularities in english is a good one. Sometimes we just need a nice influx of new examples, rather than waiting around for them to come naturally. This is why i really love Anki (or other SRS software). Certain words that i hear in a german Star Trek episode might not come up again for another 20 or 30 episodes (if ever), but if i put it into my SRS with a few example sentences, i'll be quite familiar with it, as if it were a common word.

You temporarily made "bought" a common word for your daughter, and you also gave her several ways to make mental connections to it (thereby making it more memorable) by saying "this is a weird word because it changes".

Most often, there isn't much of a "why" for these words, but i think it helps to relate them to other words that do the same thing (ie geese and mice, deer and fish). it gives you a mental place to put them, enhancing memory.